Asphalt-based compositions are used in a variety of construction and building applications. These applications include coating, sealing, waterproofing, joining, cementing, and repairing components such as roofing, walls, footings, and foundations. Such compositions are often referred to as adhesives, cements, mastics, caulking, sealants, primers and coatings.
Asphalt-based compositions are also useful for roofing applications, including the construction or repair of built-up roofs, as saturants used with asphalt roll-roofing, for sealing parapet walls and roof penetrations, and for repairs to and sealing of flashings and gutters. Asphalt compositions may also be used for repair of asphalt shingles, and filling of cracks and nail holes in shingles.
To be commercially useful, such compositions should be durable, easy to apply in a variety of conditions, and relatively inexpensive. Existing asphalt-based roofing composition are typically sold in tubs (ranging from one gallon to 55 gallons) and tubes, and can be applied via trowel or with a caulk gun dispenser.
There are other specialty applications for asphalt-based compositions, including, for example, joint and crack fillers, waterproofing and damp-proofing applications, and tank and pipeline coatings. Compositions designed for such applications typically have their own set of requirements, and are manufactured to meet different ASTM standards.
Asphalt-based roofing compositions are available in a wide variety of grades, typically for use in different applications and temperatures. For built-up roofs, grade is described in ASTM D312 according to the material softening point. Specifically, a Type I roofing asphalt has a low softening point and is considered a soft composition. A Type IV roofing asphalt has a high softening point and is considered a hard composition. These, and intermediate grade compositions, are based on the susceptibility of the asphalt to flow at stated roof temperatures and slopes.
Asphalt-based compositions for roofing and other applications include a solvent to keep the composition soft and pliable, so that it can be readily applied. Once applied, the solvent evaporates, leaving residual asphalt and other ingredients in the compositions. Although the solvents vary depending on the manufacturer, grade, and intended application, existing products employ solvents such as naphtha, kerosene, gasoline, and fuel oil. These compounds are known as volatile organic compounds (VOCs), which contain carbon and evaporate (become a vapor) or “off-gas” at room temperature. Additional VOC solvents include benzene, xylene, methylene chloride, hexane, toluene, trichloroethane, styrene, heptane, methyl-ethyl ketone, butyl acetate and perchloroethylene.
For example, EP1811004 to Kelly et al. discloses asphalt-based compositions comprising asphalt, solvent, clay, and a propoxylated alcohol-based ether amine salt surfactant. The disclosed compositions utilize solvents that contain VOCs.
Moss et al., U.S. Pat. No. 7,238,230, discloses asbestos-free compositions intended for use in roof construction and repair, pavement construction and repair, or as a protective coating for building surfaces. The compositions comprise asphalt, solvent, clay and a propoxylated alcohol-based ether amine salt surfactant. The disclosed compositions include solvents that contain VOCs.
Krogh et al., U.S. Pat. No. 5,730,791, discloses asbestos-free compositions comprising asphalt, solvent, clay, and a hindered acid/amine salt surfactant. The surfactant comprises an acid constituent that has at least two alkyl groups bonded to an alpha carbon and an amine constituent comprising a variety of primary, secondary and tertiary amines. Again, the solvents in the disclosed compositions contain VOCs.
In recent years, there has been widespread concern associated with the use of VOCs, which can cause environmental damage and impact human health. Accordingly, governmental agencies and environmental organizations have sought to limit their use. New regulations have limited the use of VOC containing, solvent-based products. Accordingly, there is a need for low- or no-VOC compositions, which may be described as VOC-free.
In response to concerns and regulations governing the use of VOCs, some manufacturers have introduced asphalt-based compositions that employ emulsion technology. Such technology generally involves the use of an emulsifier, which suspends asphalt particles in water or water and oil. Following application, the liquid evaporates leaving the resulting asphaltic composition. Unfortunately, use of water has certain drawbacks and limitations, including that the compositions are susceptible to freezing during storage or in use, resulting in separation of the ingredients and failure of the composition.
For all of the foregoing reasons, there is a need to develop asphalt-based compositions for roofing and other applications that are low- or no-VOC, and which do not employ emulsion-technology. Specifically, there is a need for low- or no-VOC asphalt-based compositions which can provide enhanced performance over VOC-containing compositions at a reasonable cost.
It is an object of the present invention to provide asphalt-based compositions that are environmentally safe.
It is a further object of the invention to provide asphalt-based compositions that contain biodegradable solvents that are low- or no-VOC, and which may be described as VOC-free.
It is also an object of the invention to provide VOC-free asphalt-based compositions that can be easily applied and which are useful for roofing applications, such as roofing cements, flashing cements, coatings, and primers. Depending on the composition and application, such compositions may be applied via trowel, caulk gun, or other types of applicators, in a fashion similar to existing VOC-containing compounds.
It is a further object of the invention to provide VOC-free asphalt-based compositions that exhibit good pliability, workability, flexibility and adhesion, without sagging, slipping, or disbanding under a variety of temperatures.
It is another object of the invention to provide VOC-free asphalt-based composition that may be useful for applications such as water proofing, tank lining, and pipe coating or coating of footings and foundations.
It is a further aspect of the invention to provide VOC-free asphalt-based compositions that may be manufactured in a variety of grades for use in different regions of the world, and for various environmental conditions. Such compositions may also include functional fillers to enhance thixotropic properties, fibers for strength and resilience, and aluminum flakes or colorants for appearance or to limit the absorption of heat.
It is also an object of the invention to provide a method of manufacturing compositions meeting the foregoing objects.